Map Types with ggmap

Gliederung

Arten von räumlichen Daten:

• Straßenkarten
• Satelliten Bilder
• Physische Daten und Karten
• Abstrakte Karten
• …

Das R-paket ggmap wird im folgenden genutzt um verschiedene Kartentypen darzustellen.

Mit qmap kann man eine schnelle Karte erzeugen.

Straßenkarten

Mannheim

A road map is one of the most widely used map types.

• These maps show major and minor highways and roads (depending on detail)
• as well as things like airports, city locations and points of interest like parks, campgrounds and monuments.
• Major highways on a road map are generally red and larger than other roads,
• while minor roads are a lighter color and a narrower line.

Road maps

Install the library

• We’ll need package ggmap - so we have to install it:

1. possibility

install.packages("ggmap")

2. possibility:

Library ggmap - Hallo Welt

• To load the library we use the command library

library(ggmap)

qmap("Mannheim")

Karte für eine Sehenswürdigkeit

BBT <- qmap("Berlin Brandenburger Tor")
BBT

Karte für einen ganzen Staat

qmap("Germany")

• We need another zoom level

Use another zoom level

• level 3 - continent
• level 10 - city
• level 21 - building

qmap("Germany", zoom = 6)

Get help with the questionmark

?qmap

Different components in the help

• Description
• Usage
• Arguments
• Value
• Author(s)
• See Also
• Examples

The examples section of help

Extract from the help file on qmap:

This examples can be directly copy-pasted to the console

qmap("baylor university")
qmap("baylor university", zoom = 14)
# and so on

Other zoom level

qmap("Mannheim", zoom = 12)

Get closer

qmap('Mannheim', zoom = 13)

Get very close

qmap('Mannheim', zoom = 20)

ggmap - source OpenStreetMap

qmap('Mannheim', zoom = 14, source="osm")

ggmap - OpenStreetMap - black/white

qmap('Mannheim', zoom = 14, source="osm",color="bw")

ggmap - maptype satellite

qmap('Mannheim', zoom = 14, maptype="satellite")

ggmap - maptype satellite zoom 21

qmap('Mannheim', zoom = 21, maptype="hybrid")

ggmap - maptype hybrid

qmap("Mannheim", zoom = 14, maptype="hybrid")

Terrain/physical maps

Physical maps illustrate the physical features of an area, such as the mountains, rivers and lakes. Colors are used to show relief differences in land elevations.

• The water is usually shown in blue.
• a lighter color is typically used at lower elevation and
• darker color indicate higher elevations.
• Contour lines can also be used to show elevation changes (they are normally spaced at regular intervals)

ggmap - terrain map

qmap('Schriesheim', zoom = 14,
 maptype="terrain")

Abstracted maps

Source: Design faves

• Abstraction is used to create a map with only essential information
• Example metro maps - directions and little information for orientation is included
• In the following especially background maps

ggmap - maptype watercolor

qmap('Mannheim', zoom = 14,
 maptype="watercolor",source="stamen")

ggmap - source stamen

qmap('Mannheim', zoom = 14,
 maptype="toner",source="stamen")

ggmap - maptype toner-lite

qmap('Mannheim', zoom = 14,
 maptype="toner-lite",source="stamen")

ggmap - maptype toner-hybrid

qmap('Mannheim', zoom = 14,
 maptype="toner-hybrid",source="stamen")

ggmap - maptype terrain-lines

qmap('Mannheim', zoom = 14,
 maptype="terrain-lines",source="stamen")

Stamen maps

These high-contrast B+W (black and white) maps are featured in our Dotspotting project. They are perfect for data mashups and exploring river meanders and coastal zones.

Source: http://maps.stamen.com/

Save graphics

ggmap - create an object

• <- is an assignment operator which can be used to create an object
• This is useful if you work with several maps at the same time

MA_map <- qmap('Mannheim', 
               zoom = 14,
               maptype="toner",
               source="stamen")

Geocoding

Geocoding (…) uses a description of a location, most typically a postal address or place name, to find geographic coordinates from spatial reference data …

Wikipedia - Geocoding

library(ggmap)
geocode("Mannheim Wasserturm",source="google")

lon	lat
34.79565	32.1221

Latitude and Longitude

Source

Coords of different places in Germany

cities	lon	lat
Hamburg	9.993682	53.55108
Koeln	6.960279	50.93753
Dresden	13.737262	51.05041
Muenchen	11.581981	48.13513

Reverse geocoding

Reverse geocoding is the process of back (reverse) coding of a point location (latitude, longitude) to a readable address or place name. This permits the identification of nearby street addresses, places, and/or areal subdivisions such as neighbourhoods, county, state, or country.

Source: Wikipedia

revgeocode(c(48,8))

## [1] "Unnamed Road, Somalia"

Get the distance between 2 points

mapdist("Q1, 4 Mannheim","B2, 1 Mannheim")

mapdist("Q1, 4 Mannheim","B2, 1 Mannheim",mode="walking")

Get another distance

mapdist("Q1, 4 Mannheim","B2, 1 Mannheim",mode="bicycling")

Take Home Messages/Homework

What you should know:

• How to create a quick map
• How to get a geocode
• How to compute a distance

Homework:

• Please send me a map of a place/city you like very much

And now some more advanced stuff….

Geocoding - various points of interest

POI1 <- geocode("B2, 1 Mannheim",source="google")
POI2 <- geocode("Hbf Mannheim",source="google")
POI3 <- geocode("Wasserturm Mannheim",source="google")
ListPOI <-rbind(POI1,POI2,POI3)
POI1;POI2;POI3

##        lon      lat
## 1 8.462844 49.48569

##        lon      lat
## 1 8.469879 49.47972

##        lon      lat
## 1 8.466039 49.48746

Points in map

MA_map +
geom_point(aes(x = lon, y = lat),
data = ListPOI)

Points in map

MA_map +
geom_point(aes(x = lon, y = lat),col="red",
data = ListPOI)

ggmap - adding different colors

ListPOI$color <- c("A","B","C")
MA_map +
geom_point(aes(x = lon, y = lat,col=color),
data = ListPOI)

ggmap - bigger dots

ListPOI$size <- c(10,20,30)
MA_map +
geom_point(aes(x = lon, y = lat,col=color,size=size),
data = ListPOI)

Get a route from Google maps

from <- "Mannheim Hbf"
to <- "Mannheim B2 , 1"
route_df <- route(from, to, structure = "route")

More information

Draw a map with this information

qmap("Mannheim Hbf", zoom = 14) +
  geom_path(
    aes(x = lon, y = lat),  colour = "red", size = 1.5,
    data = route_df, lineend = "round"
  )

Resources

• Article by David Kahle and Hadley Wickham on the usage of ggmap.
• Grab a map
• Making Maps in R

More about adding points

• Usage of geom_point
• Question on stackoverflow

Cheatsheet

• Cheatsheet on data visualisation

Resources and literature

ggmap: Spatial Visualization with ggplot2

by David Kahle and Hadley Wickham